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Na et al., IEEE TSMC 52(8), 2022 · interactive reproduction

Quarter-Car AFC Lab

Run the paper's approximation-free controller on an electro-hydraulic quarter car. The controller samples at 50 Hz and the valve is limited to ±5 V. The plant is integrated with RK4 using the same equations as the project's MATLAB library, so these numbers match afc2 exactly.

Road
Controller
Plant

Defaults reproduce the paper's Case 10 run: 43 mm at 0.505 Hz, Case A gains, μ1(t) = (0.2 − 0.018)e−3t + 0.018 m.

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What AFC does near zero error

Inside the envelope the logarithm is close to linear, so AFC acts like a cascade of proportional loops. As |zs| approaches μ1 the barrier raises the gain sharply. That is how the bound is enforced, and it is also why a slow or saturated valve turns AFC into bang-bang control.